GENETICS
MR NKOSI J.
LIFE SCIENTIST: UMJINDI CIRCUIT
2024/04/18 Prepared by: Mr Nkosi J. – Life Scientist from Umjindi Circuit 2019 1
, TERMINOLOGY
Monohybrid cross
Only one characteristic/hereditary trait is investigated at a
time. Gr.12 Life Sciences
Mendel’s Law of Segregation
Each characteristic is regulated by two alleles/factors which
separate during meiosis so that each gamete contains only
one of the alleles/factors.
Mendel’s Principle of Dominance
When two individuals with pure breeding contrasting
characteristics are crossed,the F 1-generation all display the
dominant characteristic.
2024/04/18 Prepared by: Mr Nkosi J. – Life Scientist from Umjindi Circuit 2019 2
, TERMINOLOGY
Complete dominance
A genetic interaction where one allele of a gene supress
the expression of an alternative allele in the F 1
heterozygote (e.g. Bb) so that the phenotype is the same as
that of the dominant allele.
Incomplete dominance
A pattern of inheritance in which a cross between two
phenotypically different parents produces an offspring
different from both parents but containing partial features
of both - intermediate.
Co-dominance
Both alleles are equally dominant and therefore both are
expressed in the phenotype
2024/04/18 Prepared by: Mr Nkosi J. – Life Scientist from Umjindi Circuit 2019 3
MR NKOSI J.
LIFE SCIENTIST: UMJINDI CIRCUIT
2024/04/18 Prepared by: Mr Nkosi J. – Life Scientist from Umjindi Circuit 2019 1
, TERMINOLOGY
Monohybrid cross
Only one characteristic/hereditary trait is investigated at a
time. Gr.12 Life Sciences
Mendel’s Law of Segregation
Each characteristic is regulated by two alleles/factors which
separate during meiosis so that each gamete contains only
one of the alleles/factors.
Mendel’s Principle of Dominance
When two individuals with pure breeding contrasting
characteristics are crossed,the F 1-generation all display the
dominant characteristic.
2024/04/18 Prepared by: Mr Nkosi J. – Life Scientist from Umjindi Circuit 2019 2
, TERMINOLOGY
Complete dominance
A genetic interaction where one allele of a gene supress
the expression of an alternative allele in the F 1
heterozygote (e.g. Bb) so that the phenotype is the same as
that of the dominant allele.
Incomplete dominance
A pattern of inheritance in which a cross between two
phenotypically different parents produces an offspring
different from both parents but containing partial features
of both - intermediate.
Co-dominance
Both alleles are equally dominant and therefore both are
expressed in the phenotype
2024/04/18 Prepared by: Mr Nkosi J. – Life Scientist from Umjindi Circuit 2019 3
